Wireless access is provided to user equipments (UEs) or other mobile devices by cellular base stations. Each cellular base station also needs backhaul, with sufficient capacity to meet the needs of every connected user simultaneously. Although backhaul is typically provided using a wired connection to the Internet or to a private operator network, in some cases backhaul is provided using a wireless connection. Wireless backhaul can be provided over a Wi-Fi connection, thus avoiding interference with the bands used for cellular access.
Wireless access is also provided to users within subways and trains, as well as other vehicles. However, providing access with the quality that users have come to expect requires expensive buildout of coverage within subterranean tunnels, and improving coverage only at train stations does not solve this problem.